Hard for me to pick one. We've been pretty blessed over the years since we've never had any kind of catastrophic failures over probably around 750,000 miles driven (knock on wood). The most reliable is probably a tie between our 1998 Acura SLX (rebranded Isuzu Trooper) and our 2013 Buick Enclave, which is still in our stable.
The Jeeps though, have been pretty stellar over the years (with the exception of the '76 CJ 7 Quadratrac problems - ya long time ago). My '84 Scrambler was bullet proof until it was totaled by a Mustang in '95. My settlement check was about what I paid for it 10 years earlier and after around 150K miles. My '04 LJ now has around 294,000 miles on it with only a handful of issues including 2 cat failures, one starter, and countless batteries, u-joints, etc. as one would expect with that many miles. My son's '15 Cherokee V6 has been trouble free for over 3 years and my '14 Grand Cherokee Overland Ecodiesel has been solid for the 4 years I've owned it (thanks to Green Diesel Engineering tunes) except for the recent EPA and EGR cooler recalls.
Worst cars I've owned were the '74 Ford Maverick in college (fill the oil, check the gas) and '88 Chrysler Lebaron which never was the same after a warped head.
Honorable mention for worst car was our '94 Toyota Camry which, besides being plain ugly and boring, just started to fall apart piece by piece.